Genomic Testing - Q&A's

1. Why do a genomic test?

Genomic testing gives twice as much genetic information on a young animal as a pedigree index.

Use genomic testing to identify the best heifers to; 1) retain as replacements
2) mate to sexed semen
3) flush as embryo dams

For males, identify potential AI candidate bulls and give more information on potential stock bulls.

2. What animals should be tested?

Heifers and young bulls are most suitable for genomic testing. These are the animals in the herd with the least known about their genetic merit but also with the highest potential type merit and PLI values.

3. What tests are available?

Holstein UK offers low density (LD) and high density (HD) tests for both males and females.

Use LD tests for most females and young bulls
Use HD tests for AI bull candidates
Use HD tests for females sired by a stock bull (which is not itself HD tested)

4. How do I go about ordering a genomic test?

Order a gKIT from Holstein UK, then decide whether you wish to use a tissue sample (taken using a suitable tag vial) or hair sample.

The gKIT has full instructions on how to take a sample, including things such as where to take the hair from and numbers needed. The kits also contain labels for return of samples.

5. How long does the process take?

6 to 8 weeks depending on what date you return the sample (data is processed in line with proof runs - a list of submission dates can be found on the website).

6. What information do I get back on my animals?

Each animal receives a full set of UK genomic type and production trait results, including the GPLI£ index.

7. How do I get the information back and where do I access results?

We make results available via the members section on the website, under 'genomic test history'. Heifer fact sheets will also be published on the public Holstein UK website

Pedigree certificates will show recessive information.

8. Is a UK test the same as a US or Canadian test?

NO, a UK test (GPLI) is the only one which will give you genetic merit in UK conditions.

US (GTPI) and Canadian (GLPI) results will give information on performance in those countries and are not relevant in UK conditions. Use of these tests should only be considered for international marketing purposes.

9. Are recessives and haplotypes included in the test?

A number of genetic tests are included in the price of the genomic test: Haplotypes, Dumps, Blad, Citrullinemia, Beta Lactoglobulin, Kappa Casein, Beta Cassein A/B and Leptin.

Additional traits can be tested using the same sample but these attract an additional cost: Coat Colour, Polled status, Beta Casein A2, Brachyspina and CVM. If you would like to discuss costs for these tests please contact us on: 01923 695202.

10. What is the difference between the unofficial and official male test?

Any male under 15 months of age can obtain an unofficial UK genomic result. This is only available to the owner and can be used to sell the bull, but is not publishable for semen marketing purposes.

If it is intended that the bull will be marketed through AI, then the result must be made official by payment of the extra fee.

11. What is the difference between a genotype and a genomic test?

The DNA code is read to produce a GENOTYPE.
The genetic merit of this genotype is measured using a GENOMIC test. (Be aware that the term genotype is also used in parentage testing)

12. What can Genomic testing tell us about parentage?

Genomic testing can identify animals with incorrect sires or dams in pedigrees, but is not as yet used to assign parentage in the Holstein UK Herdbook.

Animals with incorrect parents will need to be parentage checked via the existing method before genomic results can be released.

13. Do bulls need to be parentage tested to be eligible for genomic testing?

YES and also make sure the bull is pedigree registered.

14. Is a Genomic index such as GPLI only calculated from DNA information?

GPLI and other genomic traits are calculated from a combination of DNA and pedigree information for a young animal. About two thirds of the information comes from DNA.

As the animal gets older and milk production and/or progeny information becomes available, the DNA element of the index is reduced.

15. I didn't get results back? What percentage of tests don't produce a result?

A small number (2-3%) of genomic tests do not yield a result. These animals can be retested. This can occur due to poor sampling technique - if using hair please ensure the roots are attached to the sample while for tissue vials it is important to check there is a sample within the vial prior to postage - this is a simple visual check.

16. Can a foreign genomic test be used to produce a UK test result?

Yes, but only if the genotype file is available.

If you import an animal which has been genomic tested abroad and wish to get UK results, make sure you contact the vendor to arrange for the genotype file information to be sent to AHDB Dairy.

17. How can I request a genomic test?

Individual genomic tests can be requested during the registration process: either on the telephone or internet via WebReg.
If you wish to forward buy a quantity of tests for use on heifers across the herd over a 12 month period, we offer gKITS (with discount for quantity) - to find out more contact us on 01923 695202.

If you have any further queries about genomic testing please contact:


  • Speir House
  • Staford Park One
  • Telford
  • Shropshire
  • TF3 3BD
  • United Kingdom